This lecture covers the classification, soil and climate requirements, varieties, propagation, planting, nutrient and water management, and intercultural operations of citrus crops. Citrus, a major fruit group in India, includes important species such as oranges, lemons, limes, and mandarins. The topic emphasizes key aspects of citrus taxonomy, cultivation, varietal selection, nutrient management, and irrigation for optimal productivity and quality.
Introduction to Citrus
- Citrus spp. belong to the family Rutaceae.
- Includes oranges, lemons, limes, pummelo, and grapefruit.
- Originated in tropical and subtropical Southeast Asia.
- Third most important fruit group in India after mango and banana.
Classification of Citrus
Horticultural Groups:
- Acid group: Acid lime (C. aurantifolia), Lemon (C. limon), Citron (C. medica), etc.
- Orange group: Sweet orange (C. sinensis), Sour orange (C. aurantium).
- Mandarin group: C. reticulata, C. unshiu, C. deliciosa, Kinnow.
- Pummelo and grapefruit group: Pummelo (C. grandis), Grapefruit (C. paradisi), Kumquat (Fortunella sp.).
- Hybrids: Citrange, Tangelo, Citrangequat, used mainly as rootstocks.
Soil and Climate Requirements
- Best grown in subtropical climates, 500–1500 m MSL elevation.
- Optimal rainfall: 150–250 cm/year; mild winters preferred.
- Ideal soil: Medium/light loam, pH 5.5–6.5, well-drained.
- Acid lime prefers pH 6.5–7.0; sensitive to frost.
Important Citrus Varieties
- Kodai Orange (C. reticulata): Vigorous, small, loose rind, heavy seeded.
- Nagpur Santra (C. reticulata): Leading commercial mandarin, fine texture, juicy, matures Jan–Feb.
- Coorg Mandarin (C. reticulata): Medium-large, bright orange, regular bearer.
- Satsuma Mandarin (C. unshiu): Japanese, seedless, thin rind, excellent quality.
- Kinnow (King × Willow leaf): Hybrid, high yield, export potential.
- Khasi Mandarin: North-East India, excellent quality, polyembryonic seeds.
Propagation Methods
- Seed propagation: Used for most mandarins; select true-to-type, healthy seeds.
- Vegetative propagation: T-budding on rootstocks like Rangpur lime, Cleopatra, Rough lemon, Troyer citrange.
- Budded plants bear earlier and are more uniform.
- Rootstocks selected for disease resistance and soil adaptability.
Planting and Spacing
- Planting season: May–June and September–October (monsoon period).
- Spacing: 6 × 6 m for most mandarins; 5–6 m for acid lime.
- Pit size: 75 × 75 × 75 cm, filled with FYM, sand, and topsoil.
- High-density planting possible for Kinnow using Troyer citrange rootstock.
Training and Pruning
- Train trees to single stem with 4–6 main branches.
- Remove water shoots, rootstock sprouts, and laterals up to 45–50 cm height.
- Prune bearing trees after harvest to remove dead, diseased, and weak branches.
- Root pruning sometimes used for crop regulation.
Crop Regulation (Bahar Treatment)
- Mandarins may flower 1–3 times/year (Ambe, Mrig, Hast Bahar).
- Bahar treatment: Expose roots and withhold water to induce rest and synchronized flowering.
- Not recommended for light soils or North India.
Nutrient Management
- Apply FYM and NPK fertilizers in two splits (June and October).
- Micronutrients: Zn, Mn, Fe, Mg, B, Mo required; avoid excess Na and Cl.
- Apply lime/dolomite in acidic soils once every 2–3 years.
- Foliar sprays of micronutrients during new flushes improve growth.
Fertilizer Schedule (Example: Palani Hills)
| Year |
FYM (kg) |
N (kg) |
P (kg) |
K (kg) |
| 1 |
10 |
0.10 |
0.04 |
0.05 |
| 2 |
15 |
0.20 |
0.08 |
0.10 |
| 3 |
20 |
0.30 |
0.12 |
0.20 |
| 4 |
25 |
0.40 |
0.16 |
0.30 |
| 5 |
25 |
0.50 |
0.16 |
0.30 |
| 6+ |
30 |
0.60 |
0.20 |
0.40 |
Irrigation Management
- Young plants require regular irrigation, especially during dry spells.
- Mandarins: Water at 10–15 day intervals in winter, 5–7 days in summer.
- Avoid waterlogging; citrus is sensitive to excess moisture.
- Water should be free from salts.
Weed Control and Intercropping
- Weeds compete for nutrients and water, especially in young orchards.
- Pre-emergence herbicides: Diuron (5 kg/ha), Terbacil (4.5 kg/ha).
- Post-emergence: Atrazine (5–6 kg/ha), Glyphosate (5 L/ha).
- Intercropping with legumes (pea, cowpea, blackgram) is beneficial during pre-bearing years.
Growth Regulators
- 2,4-D (20 ppm) or NAA (30 ppm) sprayed at flowering and marble stage increases fruit retention.
- Improves fruit set and reduces premature fruit drop.
Harvest and Yield
- Budded plants bear in 3–5 years; seedlings in 5–7 years.
- Yield: 15–20 t/ha/year; 1000–1500 fruits/tree/year at full bearing.
- Harvest when fruits are full-sized, colored, and have optimal sugar-acid blend.
- Use clippers or secateurs to avoid skin damage.
Post-Harvest Handling and Storage
- Grade fruits by size and appearance; pack in wooden boxes or CFB cartons.
- Store at 8–10°C, 85–90% RH for best shelf life.
- HDPE/poly bags with ventilation extend storage life of Kinnow and Nagpur Santra.
- Waxing and neem leaf extract reduce post-harvest losses.
Summary of Citrus Cultivation
- Citrus requires careful varietal selection, proper soil, and climate management.
- Judicious nutrient and water management are essential for high yield and quality.
- Integrated weed, pest, and disease management improve orchard health.
- Proper post-harvest handling ensures better market returns.
Objective Questions
Q1. Which subgenus do all edible citrus fruits belong to?
A. Eucitrus
B. Fortunella
C. Poncirus
D. Citrus
Answer: A
Q2. Which citrus group is characterized by loose skin of fruits?
A. Acid group
B. Orange group
C. Mandarin group
D. Pummelo group
Answer: C
Q3. Which rootstock is most salt tolerant for mandarins?
A. Rangpur lime
B. Cleopatra mandarin
C. Rough lemon
D. Troyer citrange
Answer: B
Q4. What is the ideal soil pH range for citrus cultivation?
A. 4.0–5.0
B. 5.5–6.5
C. 7.0–8.0
D. 6.5–7.5
Answer: B
Q5. Which micronutrient is NOT required by mandarins and is considered harmful?
A. Zinc
B. Boron
C. Sodium
D. Manganese
Answer: C
Q6. What is the recommended spacing for Nagpur mandarin budded on Rough lemon?
A. 4.5 x 4.5 m
B. 5 x 5 m
C. 6 x 6 m
D. 1.8 x 1.8 m
Answer: C
Q7. Which growth regulator is used at 20 ppm to increase fruit retention in citrus?
A. GA3
B. 2,4-D
C. Ethrel
D. IAA
Answer: B
Q8. Which weedicide is recommended for pre-emergence weed control in mandarin nurseries?
A. Atrazine
B. Diuron
C. Glyphosate
D. Simazine
Answer: B
Q9. What is the main harvesting period for mandarins in North-Eastern India?
A. Dec–Feb
B. Feb–March
C. Nov–Feb
D. July–August
Answer: C
Q10. Which mandarin cultivar is a hybrid between King and Willow Leaf mandarins?
A. Ponkan
B. Kinnow
C. Dancy
D. Clementine
Answer: B